Recently, a four-leg walking pet robot which acts in accordance with the user's command and surrounding environment has been proposed and developed by the patent applicant(s) of this invention. The pet robot has the shape like a dog or a cat had in a common home, and autonomically acts in accordance with the user's command and surrounding environment. Note that the assembly of movements is defined as an action to be used hereinafter.
Moreover, the patent applicant(s) of this invention has proposed the method of improving the sense of amusement as a pet robot in such a way that the “growth” function is provided in the pet robot, like a real dog or cat, to give an user the sense of affinity and feeling of satisfaction (Japanese Patent Application No. 129276/1999).
However, in the pet robot which has been disclosed in the Japanese patent application No. 129276/1999, since the level of difficulty or complication in the actions and movements expressed (hereinafter, this is referred to as growth level) is only raised up in stages, there is a problem that a user becomes accustomed to the actions and movements of the pet robot and gets tired of them, for example, in the case where the pet robot has been “grown up” or in the case where there is a long term before the next “growth”.
Also, since the pet robot determines the actions and movements in accordance with the predetermined program, a plurality of pet robots which are in the same growth stage perform the same actions and movements, for example, when the commands given by a user and surrounding environment are same. Thereby, it is difficult to grow up the pet robot performing the actions and movements specific to the user.
Accordingly, in the pet robot, if the above problems can be solved, it can be considered that the user does not get tired of the pet robot and the sense of amusement is further improved.